Cementing sub for annulus cementing

ABSTRACT

A cementing sub for wellbore annulus cementing that allows certain regions of the wellbore annulus to be cemented while other regions are left open for perforating, activation or controllable ported access. The cementing sub may include a tubular body including a first end, an opposite end and a wall defined between an inner bore extending from the first end to the opposite end and an outer surface; a port through the wall of the tubular body providing communication between the inner bore and the outer surface, the port including an openable closure; a conduit along the wall of the tubular extending from an inlet adjacent the first end and an outlet adjacent the opposite end, the inlet and outlet opening to the outer surface and being isolated from communication with the inner bore; a first annular packer encircling the tubular body and positioned between the port and the inlet; and a second annular packer encircling the tubular body and positioned between the port and the outlet.

FIELD

The present invention relates to downhole tubulars and, in particular, awellbore tubular device for assisting annulus cementing operations.

BACKGROUND

Wellbores are often completed by introduction of cement around thetubular in the annulus between the tubular and the borehole wall. Thecement holds the tubular in place in the well and creates isolation bycontrolling against fluid passage through the wellbore annulus from onesection of the well to another. Isolation serves the purpose ofpreventing flow of fluids or gas from one section of a well that may beundesirable such as water, to a section of the well that would otherwiseproduce hydrocarbon.

In addition, certain operations require that fluid be placed into thewell at specific locations. These operations may include acidizing orhydraulic fracturing. The cement in these cases provides isolation bycontaining the fluid placement to the desired locations in the well toproduce desired results. If ports are placed along a tubular string inthe well, either cement or packers can be used to isolate one section ofthe well about one or more ports from one another section. If the portsare cemented in place, the cement circulated into the annulus section ofthe well may cause problems operating the ports. In addition, theability to inject fluid into the formation through the ports may provedifficult because the cement will prevent contact and communication withthe formation rock. If fracturing is planned, the cement may cause highfracture initiation pressures.

When a ported tubular is positioned in a well, cement generally cannotbe used in the usual way since the cement will block the outside of theport such that although the port is opened, fluid treatments are blockedfrom entering the wellbore because of the presence of the cement. Iffluid is introduced at a pressure that would normally fracture the well,the force of the fluid injection is distributed over a wider area by thecement such that the force is dissipated and the treatment may berendered less than effective.

SUMMARY

The invention relates to a wellbore tubular for assisting annuluscementing operations by allowing some sections of the well to be leftuncemented and to provide the option to either perforate or to activateor open and close ports within these uncemented areas.

If ports are used and the annulus surrounding the ports is not cemented,but the adjoining areas on each side of the ports contain a cementedannulus, then the ports, when opened, will provide direct contact withthe formation for production or fluid placement (formation stimulation),and the benefits of cement to perform zonal isolation.

This invention provides a wellbore tubular, a method and a wellboretubular installation to allow cementing of the annulus while leaving thearea surrounding the ports uncemented.

In accordance with a broad aspect of the present invention, there isprovided method for installing a tubular string in a wellbore, themethod comprising: providing a tubular string including an inner boreand an outer surface, an upper annular packer encircling the tubularstring, a lower annular packer encircling the tubular string below theupper annular packer and a conduit extending to provide a fluid tightpath from a conduit first open end below the lower packer incommunication with the outer surface and a conduit second open end abovethe upper packer in communication with the outer surface; running thetubular string into the wellbore to create an annulus between thetubular string and the wellbore wall; setting the packers to isolate anintermediate portion of the annulus from annular regions above the upperpacker and below the lower packer; pumping cement into the annularregions and through the conduit, such that the conduit and the annularregions above the upper packer and below the lower packer become filledwith cement while the intermediate portion of the annulus is isolatedfrom introduction of cement thereto; and allowing the cement to set.

In accordance with another broad aspect of the present invention, thereis provided a wellbore tubular comprising: a tubular body including afirst end, an opposite end and a wall defined between an inner boreextending from the first end to the opposite end and an outer surface; aport through the wall of the tubular body providing communicationbetween the inner bore and the outer surface, the port including anopenable closure; a conduit along the wall of the tubular extending froman inlet adjacent the first end and an outlet adjacent the opposite end,the inlet and outlet opening to the outer surface and being isolatedfrom communication with the inner bore; a first annular packerencircling the tubular body and positioned between the port and theinlet; and a second annular packer encircling the tubular body andpositioned between the port and the outlet.

In accordance with another broad aspect of the present invention, thereis provided a tubular installation in place in a borehole comprising: atubing string in a borehole creating an annular space between the tubingstring and a wall of the borehole, the tubing string including a tubularbody including a first end, an opposite end and a wall defined betweenan inner bore extending from the first end to the opposite end and anouter surface; a port through the wall of the tubular body, which whenopen provides communication between the inner bore and the outersurface; a conduit along the wall of the tubular extending from an inletadjacent the first end and an outlet adjacent the opposite end, theinlet and outlet opening to the outer surface but being isolated fromcommunication with the inner bore; a first annular packer encircling thetubular body and expanded to seal against communication between the portand the inlet; and a second annular packer encircling the tubular bodyand expanded to seal against communication between the port and theoutlet, the first packer and the second packer dividing the annularspace into an upper annular space above the second packer, a middleannular space between the first packer and the second packer and a lowerannular space below the first packer.

It is to be understood that other aspects of the present invention willbecome readily apparent to those skilled in the art from the followingdetailed description, wherein various embodiments of the invention areshown and described by way of illustration. As will be realized, theinvention is capable for other and different embodiments and its severaldetails are capable of modification in various other respects, allwithout departing from the spirit and scope of the present invention.Accordingly the drawings and detailed description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings, several aspects of the present invention areillustrated by way of example, and not by way of limitation, in detailin the figures, wherein:

FIG. 1 is a schematic sectional view along a portion of a well bore witha tubular therein, according to one aspect of the invention.

FIG. 2 is a sectional view along a portion of a well bore with a tubularstring therein.

FIG. 3 is a perspective view of a wellbore tubular according to thepresent invention.

FIG. 4 is a sectional view along the long axis of another wellboretubular according to the present invention.

DESCRIPTION OF VARIOUS EMBODIMENTS

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various embodiments of thepresent invention and is not intended to represent the only embodimentscontemplated by the inventor. The detailed description includes specificdetails for the purpose of providing a comprehensive understanding ofthe present invention. However, it will be apparent to those skilled inthe art that the present invention may be practiced without thesespecific details.

With reference to the FIG. 1, a wellbore tubular and an installation areshown according to various aspects of the present invention.

A wellbore tubular may include tubular body 10 including a first end, anopposite end and a wall defined between an inner bore 10 a extendingfrom the first end to the opposite end and an outer surface 10 b; one ormore ports 18 through the wall of the tubular body providingcommunication between the inner bore and the outer surface, each portincluding an openable closure 20; a conduit 24 along the wall of thetubular extending between openings from the area around the outersurface to the conduit. For ease of reference, the openings can beconsidered to include an inlet 26 adjacent the first end and an outlet28 adjacent the opposite end. The inlet and the outlet open to the outersurface but are isolated from communication with inner bore 10 a of thetubular. In this way fluids can pass through the conduit from the inletto the outlet (or vice versa) along the wall of the tubular withoutflowing from the conduit out through the ports toward the outer surfaceof the tubular body and without flowing from the conduit into the innerdiameter of the tubular. As will be appreciated, the port and theconduit are out of fluid communication. For example, the conduit mayextend along the wall and the port may pass through the wall without theport and conduit opening into each other.

The wellbore tubular further may include a first annular packer 30encircling the tubular body and positioned between port 18 and the inlet26 and a second annular packer 36 encircling the tubular body andpositioned between the port and outlet 28.

The ports and their openable closures may take various forms. Forexample, the openable closures may include burst discs, dissolvablematerials, a shearable cap, a sliding sleeve valve (as shown), etc.

The conduit may take various forms. For example, the conduit may includeone or more discreet tubulars attached on or embedded in the tubularbody wall, the tubular body wall may be formed of thick materials andthe conduit may bored axially therethrough, the tubular body wall mayinclude a hollow annular space that defines the conduit, etc. Likewise,the inlets and outlets may take various forms such as discreet openingsfrom the outer surface into the conduit. Alternately, the inlets andoutlets may be defined by larger open areas such as the full annularopening between inner and outer tubular shells forming a hollow wall ofthe tubular body.

The annular packers may also take various forms. The packers may beexpandable, inflatable, etc. In one embodiment, the packers are solidbody-type packers such as including one or more extrudable elements. Theextrudable elements may be driven to expand by hydraulic swelling orcompression drivers. For example, one useful packer type may be ahydraulically driven compression set packer such as one available fromthe assignee of this application, under the trade name Rockseal™.

The wellbore tubular may be used to form a tubular installation forplacement in a wellbore. In such an installation an annular space 40 maybe formed between the wellbore tubular and a wall 50 of the borehole.Using a wellbore tubular such as that described above as an example, thetubular installation may include the wellbore tubular placed in thewellbore with the first annular packer and the second annular packerexpanded. In such an installation, the first packer and the secondpacker divide the annular space into an upper annular space above thesecond packer, an intermediate annular space 40 a between the firstpacker and the second packer and a lower annular space below the firstpacker. When set against a wellbore wall (cased or open hole), the firstannular packer seals against communication between the port and theinlet through the annular space and the second annular packer sealsagainst fluid communication along the annular space between the port andthe outlet.

Such an installation may be employed to affect a method for installing atubular string in a wellbore. According to one embodiment, the methodmay include first providing a tubular including a port extending from aninner bore of the tubular to open on the outer surface, an upper annularpacker encircling the tubular above the port, a lower annular packerencircling the tubular below the port and a conduit extending to providea fluid path from a conduit first open end below the lower packer and aconduit second open end above the upper packer. Such a tubular can runinto the wellbore, thereby creating an annulus between the tubular and awall of the wellbore. Of course, the tubular will likely be installed ina string of tubulars and is run in by running in the string, by methodswell known in the art. In such an embodiment, the inner bore of thetubular may be in communication with the surface through an upper stringextending above the tubular. Once in position in the wellbore, thepackers may be set to isolate an intermediate portion of the annulusfrom regions of the annulus above the upper packer and below the lowerpacker. Thereafter, cement may be pumped (arrows C) into through theannular regions and through the conduit.

The conduit allows the cement to pass from the regions below the lowerpacker to the regions above the upper packer without cementing theintermediate annular region. Closures on the ports prevent the cementfrom passing into the intermediate annular region through the port. Assuch the tubular can be annularly cemented into the wellbore whileleaving the annular area about the port of the tubular open. As suchfluids can pass from the inner bore of the tubular out into contact withthe wellbore (and vice versa) without hindrance by cement in the annularregion about the port.

It will be appreciated that cement is usually pumped through the tubularinner bore from surface to an end of the tubular. Pumping is continuedsuch that the cement then moves up through the annular space about thetubular back toward surface. However, it is to be understood that themethod encompasses, and the wellbore tubular is useful for, a procedurewhere cement is pumped down towards the upper packer and passes throughthe conduit to exit below the lower packer.

After the cement is pumped through the annular space, the cement isallowed to set as by holding the cement in the annular space by holdingpressure above the cement or by use of a cement float. Thereafter, theports may be opened by, for example, opening or removing the closures.Wellbore operations can then begin, for example, production or wellboretreatments though the port such as for example by injection offracturing fluid, stimulation fluids, etc.

With reference to FIG. 2, a wellbore installation could include a string60 incorporating one or, as shown, more of the wellbore tubularsaccording to the invention such as, for example, as shown in any one ofFIG. 1, 3 or 4 or others not specifically illustrated. While twotubulars are shown, the string could include many such tubulars andpossibly other components. The tubulars include a port 18 extending froman inner bore 10 a of the tubular to open on the outer surface 10 b, anupper annular packer 36 encircling the tubular above the port, a lowerannular packer 30 encircling the tubular below the port and a conduit 24extending to provide fluid communication between the outer surface belowthe lower packer and the outer surface above the upper packer withoutopening into the outer surface between the packers. The inner bores 10 aof the tubulars are open to the inner diameter 60 a of the string 60.

Such a string 60 can run into a wellbore 50, thereby creating an annulus40 between the string and the wall of the wellbore. Of course, thetubular will likely be installed in a string of tubulars and is run inby running in the string, by methods well known in the art. Once inposition in the wellbore, the packers may be expanded or allowed toexpand to isolate an intermediate portion 40 a of the annulus fromregions of the annulus above the upper packers and below the lowerpackers. Thereafter, cement may be pumped through the annular regionsand through the conduits. In the illustration of FIG. 2, the cement canbe seen, as shown by stippling, in the annular region 40 about thestring but not in the intermediate portions 40 a between the packers ofthe tubulars. In this way, the intermediate portions 40 a remain opensuch that when ports 18 are opened, fluids can pass through inner bore60 a of the string, which is continuous with inner bores 10 a of thetubulars, and out through the ports into contact with the wellborewithout hindrance by cement in the annular region about the port.Fluids, for example, may effect a fracing operation such as that shownwherein fractures 62 are generated in the formation about the wellbore.

The ports may be opened by various means such as by tubing manipulation,bursting, shearing, etc. For example, the ports may be opened byshearing as disclosed in applicant's corresponding U.S. Pat. No.6,907,936, issued Jun. 21, 2005 or by a sliding sleeve type valve asmore fully disclosed in applicant's U.S. Pat. No. 7,134,505, issued Nov.14, 2006. Alternately or in addition, the ports may be opened all atonce, as by use of a hydraulically openable valve as disclosed inapplicants corresponding PCT application PCT/CA2009/000599, filed Apr.29, 2009. Alternately, the ports may be opened in stages, as more fullydisclosed in applicant's U.S. Pat. No. 7,134,505, issued Nov. 14, 2006.

With reference to FIG. 3, another wellbore tubular is shown according tovarious aspects of the present invention. This wellbore tubular is shownsectioned through its tubular body 110 just below its ports 118. Ends110 c and the other of which cannot be seen in this view, include forms,such as threading as shown for connection into a tubular string. As willbe appreciated, such a tubular is often called a sub. Ports 118 extendlaterally out through the wall of the tubular body providingcommunication between the tubulars inner bore and its outer surface. Asliding sleeve valve 120, shown partially open in this view, acts as anopenable closure for the ports.

A plurality of conduits 124 are formed along the wall of the tubular byattaching axial tubular segments to the outer surface of the tubular.The conduits extend from upper and lower open ends 128, only one ofwhich can be seen in this view. First and second annular packers 132,only one of which can be seen in this view, are installed about thetubular. The conduits pass through the packers and along the tubularwall to provide a fluid passage along the wall of the tubular withoutopening to the outer surface of the tubular between the packers and orinto the inner bore of the tubular.

With reference to FIG. 4, yet another wellbore tubular is shownaccording to various aspects of the present invention. This wellboretubular is shown sectioned along its long axis through a port 218. Ends210 c, while shown as blanks, can be formed to allow connection of thetubular body 210 into a tubular string. As will be appreciated, such atubular is often called a sub. Port 218 extends laterally out throughthe wall of the tubular body providing communication between the tubularbody inner bore 210 a and its outer surface 210 b. A sliding sleevevalve 220, in this view shown closed but in the process of being opened,acts as an openable closure for the port 218.

In this illustrated embodiment, the sliding sleeve is moveable remotelyfrom its closed port position, substantially as shown, to its positionpermitting through-port fluid flow, for example, without having to runin a line or string for manipulation thereof. In one embodiment, thesliding sleeve is actuated by a device, such as a ball 221 (as shown) orplug, which can be conveyed by gravity or fluid flow through the tubingstring. The device, in this case ball 221, engages against the sleeveand, when pressure is applied through the inner bore 210 a, as fromsurface through a string to the tool, ball 221 seats against and createsa pressure differential above and below the sleeve which drives thesleeve toward the lower pressure side.

In the illustrated embodiment, the inner surface of the sleeve which isopen to the inner bore 210 a of the sub defines a seat 223 onto which asuitably sized ball, when launched from surface, can land and sealthereagainst. When the ball seals against the sleeve seat and pressureis applied or increased from surface, a pressure differential is set upwhich causes the sliding sleeve on which the ball has landed to slide toa port-open position. When the port 218 is opened, fluid can flowtherethrough to the annulus between the tubing string and the wellboreand thereafter into contact with formation.

A conduit 224 is formed along the wall of the tubular body by attachingan axial tubular segment to the outer surface of the tubular. The axialtubular segment can, for example, be obtained from a pipe having aradius smaller than the radius of the wellbore tubular and a section ofthe wall of the tubular can be cut along the tubular's lengthsubstantially parallel to the long axis of the tubular. Alternately, theaxial tubular segment can be obtained by bending a sheet of materialalong its length. In any event, the axial tubular segment is attachedwith its concave side facing against the outer surface of the wellboretubular, as by welding, etc. The conduit extends between open ends 228,only one of which can be seen in this view. First and second annularpackers 232 are installed about the tubular body. The conduits passthrough the packers, when they are expanded, and along the tubular wallto provide a fluid passage along the wall of the tubular without openingto the outer surface of the tubular between the packers and or into theinner bore of the tubular.

Although other types of packers may be employed, in the illustratedembodiment, packers 232 are shown as the type set by hydrauliccompression. Such a packer includes an extrudable packing element 266carried in an unset condition which is driven to extrude by ahydraulically actuated setting mechanism 268. These parts are mounted onthe tubular body and radially outwardly of the conduit. Element 266 isformed of an elastomer, such as for example, rubber and may include anenlarged cross section to provide excellent expansion ratios to set inoversized holes.

Packing element 266 may be, for example, mounted between a fixed stopring 268 a and compressing ring 268 b. The hydraulically actuatedsetting mechanism may include a port 268 c through the tubular bodywhich provides fluid access to a hydraulic chamber 268 d defined behindcompressing ring 268 b. Compressing ring 268 b includes a piston face268 e against which the hydraulic pressure in chamber 268 d acts todrive the ring against the packing element to compress and, therefore,expand it outwardly.

Thus, the packers illustrated in FIG. 4 are set by pressuring up thetubing string such that fluid enters the hydraulic chamber and acts todrive compression of the packing elements, thereby extruding themoutwardly. A lock may be provided to act against retraction of thepacking elements out of the extruded position.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to those embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein, but is to beaccorded the full scope consistent with the claims, wherein reference toan element in the singular, such as by use of the article “a” or “an” isnot intended to mean “one and only one” unless specifically so stated,but rather “one or more”. All structural and functional equivalents tothe elements of the various embodiments described throughout thedisclosure that are know or later come to be known to those of ordinaryskill in the art are intended to be encompassed by the elements of theclaims. Moreover, nothing disclosed herein is intended to be dedicatedto the public regardless of whether such disclosure is explicitlyrecited in the claims. No claim element is to be construed under theprovisions of 35 USC 112, sixth paragraph, unless the element isexpressly recited using the phrase “means for” or “step for”.

1. A method for installing a tubular string in a wellbore, the methodcomprising: providing a tubular string including an inner bore and anouter surface, an upper annular packer encircling the tubular string, alower annular packer encircling the tubular string below the upperannular packer and a conduit extending to provide a fluid tight pathfrom a conduit first open end below the lower packer in communicationwith the outer surface and a conduit second open end above the upperpacker in communication with the outer surface; running the tubularstring into the wellbore to create an annulus between the tubular stringand the wellbore wall; setting the packers to isolate an intermediateportion of the annulus from annular regions above the upper packer andbelow the lower packer; pumping cement into the annular regions andthrough the conduit, such that the conduit and the annular regions abovethe upper packer and below the lower packer become filled with cementwhile the intermediate portion of the annulus is isolated fromintroduction of cement thereto; and allowing the cement to set.
 2. Themethod of claim 1 wherein the tubular string includes a port through itswall providing communication between the inner bore and the outersurface, the port positioned in the intermediate portion, and the methodfurther comprises: opening the port after allowing the cement to set. 3.The method of claim 1 further comprising: introducing wellbore treatmentfluids to the intermediate portion from the tubular string.
 4. Themethod of claim 1 further comprising: allowing produced fluids to passthrough the intermediate portion and into the tubular string.
 5. Themethod of claim 1 wherein the tubular string includes a second set ofpackers below the lower packer and a second conduit providing a fluidcommunication channel from the outer surface below a lower-most packerof the second set of packers to the outer surface above an upper-mostpacker of the second set of packers, the method includes setting thesecond set of packers to isolate a second intermediate portion of theannulus from annular regions above the upper-most packer and below thelower-most packer; pumping cement into the annulus to fill the annularregion below the lower-most packer, the second conduit, the annularregion between the upper-most packer of the second set of packers andthe lower packer, the conduit and the annular region above the upperpacker, while the intermediate portion and the second intermediateportion of the annulus remain isolated from introduction of cementthereto.
 6. A wellbore tubular comprising: a tubular body including afirst end, an opposite end and a wall defined between an inner boreextending from the first end to the opposite end and an outer surface; aport through the wall of the tubular body providing communicationbetween the inner bore and the outer surface, the port including anopenable closure; a conduit along the wall of the tubular extending froman inlet adjacent the first end and an outlet adjacent the opposite end,the inlet and outlet opening to the outer surface and being isolatedfrom communication with the inner bore; a first annular packerencircling the tubular body and positioned between the port and theinlet; and a second annular packer encircling the tubular body andpositioned between the port and the outlet.
 7. The wellbore tubular ofclaim 6, wherein the conduit is formed of at least an axial segment of atubular carried on the tubular body wall.
 8. The wellbore tubular ofclaim 6, wherein the conduit is formed of a tubular carried on thetubular body wall.
 9. The wellbore tubular of claim 6, wherein theconduit is formed of a hollow annular space along the tubular body wall.10. The wellbore tubular of claim 6, wherein the openable closureincludes a sliding sleeve valve.
 11. The wellbore tubular of claim 6,wherein the first annular packer and the second annular packer arehydraulically settable.
 12. A tubular installation in place in aborehole comprising: a tubing string in a borehole creating an annularspace between the tubing string and a wall of the borehole, the tubingstring including a tubular body including a first end, an opposite endand a wall defined between an inner bore extending from the first end tothe opposite end and an outer surface; a port through the wall of thetubular body, which when open provides communication between the innerbore and the outer surface; a conduit along the wall of the tubularextending from an inlet adjacent the first end and an outlet adjacentthe opposite end, the inlet and outlet opening to the outer surface butbeing isolated from communication with the inner bore; a first annularpacker encircling the tubular body and expanded to seal againstcommunication between the port and the inlet; and a second annularpacker encircling the tubular body and expanded to seal againstcommunication between the port and the outlet, the first packer and thesecond packer dividing the annular space into an upper annular spaceabove the second packer, a middle annular space between the first packerand the second packer and a lower annular space below the first packer.13. The tubular installation of claim 12, wherein the conduit is formedof at least an axial segment of a tubular carried on the tubular bodywall.
 14. The tubular installation of claim 12, wherein the conduit isformed of a tubular carried on the tubular body wall.
 15. The tubularinstallation of claim 12, wherein the conduit is formed of a hollowannular space along the tubular body wall.
 16. The tubular installationof claim 12, wherein the openable closure includes a sliding sleevevalve.
 17. The tubular installation of claim 12, wherein the firstpacker and the second packer are hydraulically settable.
 18. The tubularinstallation of claim 12 further comprising a second set of packersbelow the lower packer, the second set of packers expanded to seal theannulus between the tubing string and the wall, creating a second middleannular space and a second conduit providing a fluid communicationchannel from the annulus below a lower-most packer of the second set ofpackers to the annulus above an upper-most packer of the second set ofpackers without opening into the middle annular space.